Xerographic fusing apparatus

ABSTRACT

Method and apparatus to heat fix a heat fusible xerographic powder image to a final support material in which the powder image is first transferred to a final support material and the image-bearing support material then brought into contact with a bath of pure hot liquid metal for a period of time sufficient to fix the image to the support material. The temperature of the bath is maintained at a temperature high enough to fuse the image but below that at which the support material is damaged.

United States Patent 1191 Dhoble 1 1 XEROGRAPHIC FUSING APPARATUS [75]Inventor: Praiulla S. Dhoble, Webster, NY. [73] Assignee: XeroxCorporation, Stamford,

Conn.

[22] Filed: Apr. 11, 1974 [21] Appl. No.: 459,863

Related U.S. Application Data 163] Continuation of Ser. No. 559,852.June 23, 1966,

abandoned.

{52] U.S. C1. 427/22; 427/24; 118/58, 118/637; 134/122; 165/104; 95/89;219/216; 219/388; 219/439; 219/530; 432/8; 432/59 [58] Field 01 Searchl17/17.5, 119.6, 119.8, 117/21; 118/58, 419, 428, 429, 637; 134/5,105,122;432/8, 59; 219/216, 388, 439, 530;

[451 Aug. 19, 1975 3,103,153 10/1963 Limberger 117/37 LE 3,202,5268/1965 Ostensen 117/37 LE 3,256,002 6/1966 Hudson 1l7/17.S 3,336,9068/1967 Michalchik 117/37 LE 3.515.855 ll/1968 Mix 219/388 3,567,4843/1971 White et a1. [17/1198 3,706.588 12/1972 Shimola 117/21 3.788.8731/1974 Detig [17/1198 FOREIGN PATENTS OR APPLICATIONS 951,391 3/1964United Kingdom 117/1 19.6 22.982 10/1912 United Kingdom 117/1 19.6149,849 9/1950 Australia 117/1 19.6 800,122 8/1958 United Kingdom 117/119.6

Primary Examiner-Michael Sofocleous Attorney, Agem, 0r Firm-Robert .1.Bird [57} ABSTRACT Method and apparatus to heat fix a heat fusiblexerographic powder image to a final support material in which the powderimage is first transferred to a final support material and theimage-bearing support material then brought into contact with a bath ofpure hot liquid metal for a period of time sufficient to fix the imageto the support material. The temperature of the bath is maintained at atemperature high enough to fuse the image but below that at which thesupport material is damaged.

15 Claims, 5 Drawing Figures PATENTEDAUG 1 9|975 INVENTOR.

n ,2 :24, A r TORNE rs PRAFULLA s. DHOBLE B M;

PATENTED AUG] 9 I975 FIG 3 INVENTOR. PRAFULLA S. DHOBLE PATENTEB AUG 191975 SLZZU 3 BF 3 FIG. 5

INVENTOR. PRAFULLA S. DHOBLE BY 9 Q ATTORNEYS XEROGRAPl-IIC FUSINGAPPARATUS This is a continuation of application Ser. No. 559,852, filedJune 23, 1966 and now abandoned.

This invention relates to xerographic image fusing and, in particular,to apparatus and method for effecting image fixing by placing an imagebearing support material in thermal contact with a bath of liquid metal.

In the process of xerography as disclosed in the Carlson US. Pat. No.2,297,691, issued Oct. 6, I942, a xerographic plate comprising a layerof photoconductive insulating material placed on a conductive backing isgiven a uniform electric charge over its surface. The chargedphotoconductor is then exposed to a light image of the subject matter tobe reproduced thereby discharging the photoconductive plate in the areasof greatest radiation intensity to create an electrostatic latent image.The latent image is developed with an electrostatically charged finelydivided powder, herein referred to as xerographic toner, which isbrought into contact with the photoconductive layer. The toner iselectrostatically attracted to the image areas thus developing thelatent image. Thereafter, the developed xerographic powder image iselectrostatically transferred to a support material to which it is fixedto form a permanent copy.

In the xerographic process, a variety of powder developing materials canbe employed to develop the latent image. lt has been found preferable,however, to develop images with a toner made from pigmented resinsdeveloped specifically for use in the xerographic process. Such resinshave been developed to produce dense images of high resolution havinggood graphic reproduction qualities as well as having characteristicswhich permit convenient handling and storage.

The three most prevalent types of xerographic fusing in commercial usetoday are heat fusing, vapor fusing, and a combination of pressure andheat fusing. Because of its simplicity and flexibility of application,heat fusing has received the widest commercial usage of the three. inorder to heat fuse powder images formed of powder resins, it isnecessary to heat the powder and the support material to a relativelyhigh temperature. It is undesirable, however, to raise the temperatureof the support material to a temperature at which it is damaged ordiscolored.

The method most generally employed to heat fix a xerographic powderimage has been the process of radiant heat fusing. Such a radiant heatfuser is disclosed by Eichler in US. Pat. No. 2,965,868. in radiant heatfusing, the toner image is exposed to high intensity radiant heat energyfor a period of time sufficient to plasticize or fuse the toner to thesupport material. In most applications the radiant heat source issuspended above the image bearing support material and the radiant heatenergy concentrated thereon by means of reflectors or the like. Theradiant heat energy must, therefore, travel through a medium of ambientair before reaching the surface to be heated.

It is well known in infrared spectroscopy that carbon dioxide has aremarkable ability of absorbing maximum amounts of infrared radiationwhich are present at wavelengths of about 3.0 and 4.3 microns.Similarly, water vapor will absorb infrared radiation at numerouswavelengths between 4.0 and 7.0 microns. it should be noted that bothwater vapor and carbon dioxide are found in ambient air. Thesewavelengths at which water vapor and carbon dioxide absorb maximuminfrared energy fall within a band of wavelengths at which mostefficient infrared radiant energy sources propagate heat energy (1.0 to7.0 microns).

It is obvious that ambient air conditions will vary from day to day. Forexample, the humidity content in the air, unless controlled by costlyair conditioning systems, will vary with changes in weather conditions.Likewise, carbon dioxide, which is a waste gas produced by automobileand many industrial processes, is found in varying amounts in theambient air, the exact content also being dependent upon certain weatherconditions as well as other phenomena. An extreme example of this latterprinciple of course being the smog" conditions which prevail aboutcertain industrial centers. As can be seen, radiant heat energy whichmust travel through a medium of ambient air will lose some of thisenergy before reaching the material to be heated. Therefore, a radiantheat fuser having an ambient air gap between the source and the copymaterial will produce copy which, although commercially acceptable,varies as to fusing from day to day.

It is also widely known that the most efficient sources of radiant heatenergy are bodies which emit energy at very high temperatures, theefficiency of the source being directly proportional to its operatingtemperature. Further, high efficiency sources produce infrared energywhich is concentrated within a very narrow band of wavelengths, theenergy so produced being semi-monochromatic in form.

The most efficient fusing of xerographic copy is produced when thesupport material and the toner are both rapidly raised to the sametemperature, this temperature being above the fusing temperature of thetoner but below that at which the support material is damaged ordiscolored. However, when a high temperature infrared source is used tofuse xerographic copy, this temperature balance between toner andsupport cannot be maintained because the high temperature infraredenergy is concentrating in a band of wavelengths which favors onematerial, generally the toner, over the other. Selective infrared fusingin which xerographic toner is heated in preference to the paper has beencommercially utilized but it has been found that images of low tonerdensity cannot be fused by this method because the intensity of theenergy is so high the support material becomes damaged before completefusing of low density images is obtained.

it is therefore an object of this invention to improve method andapparatus for heat fixing a heat fusable powder to a support material.

It is a further object of this invention to control positively andaccurately the temperature of the xerographic toner and the supportmaterial during heat fusing operations.

It is a still further object of this invention to provide method andapparatus to heat fuse a xerographic image uniformly within a mediumthat is self-contained and impervious to changes in ambient airconditions.

Another object of this invention is to efficiently and rapidly heat fuseareas of low toner concentration without causing injury to the supportmaterial.

Yet another object of this invention is to rapidly heat fuse axerographic image in an economic and efficient manner.

These and other objects of this invention are achieved by placing asupport material upon which is loosely adhered a powder tonedxerographic image in thermal contact with a hot bath of relatively pureliquid metal, the metal being at a temperature sufficient to fuse thepowder image but below the temperature at which the support materialwill be damaged.

For a better understanding of this invention as well as other objectsand further features thereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawings, wherein:

FIG. I is a schematic representation of a xerographic machineincorporating the fusing apparatus of this invention;

FIG. 2 is a side view of the fusing apparatus of the machine shown inFIG. 1 and embodying the present invention;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken along line 44 in FIG. 3;

FIG. 5 is a side elevational view of an alternative embodiment of thefusing apparatus found in the present invention.

In the present invention there is provided a bath of hot liquid metalcontained within an insulated housing; the bath being utilized as a heatsource to supply the energy required to heat fix a xerographic image.Although liquids are generally considered poor thermal conductors, theliquids of some metals such as lead, bismuth, and mercury, for example.all evidence relatively good thermal conductivity and have good heattransfer characteristics.

It should also be noted that the liquid metals having good heat transferproperties are also the heavy, nonwetting metals. It has been found thata bath as utilized in the present invention can be uniformly brought tooperating conditions thus providing a heat source which can be thermallycontrolled. A uniform temperature can be maintained in the bath forthree reasons: l the bath is contained within an insulated housing sothat heat leaving the system is minimized, (2) the bath is not in motionand therefore no heat losses due to forced convection or the like arepresent, and (3) the heavy liquid gives up very little of its internalenergy because of the interaction of the molecules.

Liquid metals have the unique property of not readily mixing or bondingwith other materials. For example, liquid mercury which is placed upon apiece of paper can be rolled thereon freely without wetting the paper.Likewise, a xerographic image loosely adhered to a paper supportmaterial may be brought through or over a bath of pure liquid metalwithout the metal wetting the paper support or the toner.

In the preferred embodiment of the present invention, a toner imagebearing support material is immersed in a bath of hot liquid metals sothat the hot liquid is brought into absolute contact with the entiresurface area of both the toner and the support material regardless ofthe variance in the surface contours, a feat heretofore unobtainable inxerographic heat fusing. A metal is utilized in the bath which has arelatively high specific heat so that once the bath is brought tooperating temperature the heat energy contained in the bath will be heldtherein rather than being rejected from the system. Because of therelatively high specific heat of the bath material and the uniformitywith which the bath material may be heated, it is possible to accuratelycontrol the amount of energy delivered to the material to be heatedwhich is placed in absolute contact with the bath.

Although it forms no part of the subject invention, there is shownschematically in FIG. 1 a continuous xerographic apparatus for thepurpose of illustrating a suitable environment for a liquid metal heatfuser of the subject invention.

As shown in FIG. 1, the xerographic apparatus comprises aphotoconductive layer of light-receiving surface on a conductive backingand formed in the shape of a drum, generally designated by numeral 10,which is mounted on a shaft II journaled in a frame (not shown) torotate in the direction indicated by the arrow to cause the drum surfacesequentially to pass a plurality of xerographic processing stations.Drum 10 is rotated at a constant rate through the drive action ofsynchronous motor 12.

For the purpose of the present disclosure, the several xerographicprocessing stations in the path of movement of the drum surface may bedescribed functionally, as follows:

A charging station, at which a uniform electrostatic charge is depositedon the photoconductive layer of the xerographic drum;

An exposure station, at which a light or radiation pattern of copy to bereproduced is projected onto the drum surface to dissipate the drumcharge in the exposed areas thereof and thereby form a latentelectrostatic image of the copy to be reproduced;

A transfer station, at which the xerographic powder image iselectros'tatically transferred from the drum surface to a transfermaterial or support surface; and,

A drum cleaning and discharge station, at which the drum surface isbrushed to remove residual toner particles remaining thereon after imagetransfer, and at which the drum surface is exposed to a relativelybright light source to effect substantially complete discharge of anyresidual electrostatic charge thereon.

In general, the charging apparatus 13, which may be of the typedisclosed in Walkup US. Pat. No. 2,777,957, includes a corona dischargearray of one or more corona discharge electrodes that extendtransversely across the drum surface and are energized from a highpotential source and are substantially enclosed within a shieldingmember.

Next subsequent thereto in the path of motion of the xerographic drum isan exposure station. This exposure station may be one of a number oftypes of mechanisms or member such as desirably an optical projectionsystem 14 or the like designed to project a line copy image onto thephotoconductive surface of the xerographic drum from an original as iswell known in the art.

Adjacent to the exposure station is a developing station in which thereis positioned a developer housing 15 including a lower or sump portionfor accumulating developing material 16. A bucket type conveyor I?having a suitable driving means, such as motor I8, is used to carry thedeveloping material to the upper part of the developer housing where itis cascaded down over a hopper chute 21 onto the xerographic drum.

As the developing material is cascaded over the xerographic drum, tonerparticles are pulled away from the carrier component of the developingmaterial and deposited on the drum to form powder images, while thepartially denuded carrier particles pass off the drum into the developerhousing sump. As toner powder images are formed. additional tonerparticles must be supplied to the developing material in proportion tothe amount of toner deposited on the drum. For this pur pose there isprovided a container 22 for the toner 23 to be added to the developingmaterial as needed, the toner being added at a rate determined bycontrol gate 24.

After development, the image thus formed is transferred to supportsurface web 25, which may be of paper or any other suitable material.Web 25 is continuously transported from supply spool 26 to take-up spool27 by paper handling apparatus 28, which may be of a type disclosed inCrumrine et al. US. Pat. No. 2,781,705. Paper handling mechanism 28includes a synchronous motor 3] driving take-up spool 27 and drive rolls32, while guide rolls 33 and 34 serve to direct web 25 into contactagainst a powder image on the surface of drum l0. Electrostatic transferunit 35, which may be of a type similar to unit 13, generates anelectrostatic charge to electrostatically attract the powder image fromthe surface of drum to web 25.

Thereafter, image-bearing web is transported through fuser 40 of thetype, hereinafter described in detail, whereby the developed andtransferred xerographic powder image on the web 25 is permanently fixedthereto.

The next and final station in the device is a drum cleaning anddischarge station where any powder remaining on the xerographic drumafter transfer is removed by rotating brushes and the xerographic drumis flooded with light to cause dissipation of any residual electricalcharge remaining on the xerographic drum. Thus, the residual powderimage on the surface of drum 10 after transfer is removed by brushes 36driven by motor 37 after which residual electrostatic charge isdissipated by illumination from lamp 38.

Referring now to FIGS. 24, inclusive, there is shown a preferredembodiment of the liquid metal fusing device 40 constructed inaccordance with the present invention. In this preferred embodiment, thefusing device includes the housing 41 upon which is mounted cover 42.The housing and cover are constructed of an outer shell 43 and an innershell 44 between which is located insulating material 45 so that heatgenerated within the fusing apparatus is contained therein.

A predetermined amount of metal is placed within the housing so that adesired level line is maintained when the metal is liquified. There arecommercially available metals and alloys having low melting temperaturescapable of being used in the present invention, however, it has beenfound that alloys of bismuth, lead, and antimony, which have very lowmelting temperatures l l 7F 360F) are preferable as a bath material.Such bismuth based alloys are sold commercially by the Cerro Company ofCleveland, Ohio, under various trade names.

Heat fusing is produced in the present invention by placing a heatfusable powder image bearing support material 25 in thermal contact witha bath of hot liquid metal 46 for a period of time sufficient to heatfix the toner image to the support material. Because of the intimatecontact between the hot liquid metal and the material to be heated,sufficient heat is transferred to fuse the toner image rapidly andefficiently. It has been found that pure liquid metal, that is, a metalcontaining little or no impurities, has the quality of not readilybonding or mixing with other materials and, therefore, a toned imagebearing support material may be brought through a bath of hot liquidmetal without the metal wetting either the toner or the supportmaterial.

Located in the bottom of housing 41 are a series of heating units 85comprising tubular members 87 in which are placed resistance wires 86.The heating units, which are connected to any suitable source ofelectrical power (not shown), are electrically energized so that thetemperature within the housing is raised to a level sufficient toliquify the metal contained therein. Because of the time required tobring a liquid metal bath to operating temperatures, it is advantageousto provide extra heating elements, or heating elements capable of beingelectrically overloaded, so that sufficient heat can be transferred tometal 46 to bring the bath rapidly to an operating temperature. Furthercircuitry can be provided (not shown) to maintain the fuser in a standbycondition when the automatic xerographic equipment is not in use therebyavoiding long warm-up periods.

Thermostat 88 (FIG. 4) is electrically connected to the heating units sothat a desired bath temperature can be maintained and closely controlledwithin a very narrow temperature range. For example, in order to fuseresinous powder images formed of toner most commonly used in thexerographic process, it is necessary for the toner to be placed at atemperature of approximately 240F. However, when a support material ofpaper is used, it is undesirable to raise the temperature of the papersupport material higher than approximately 380F because at theseelevated temperatures the support material will become rapidlydiscolored. Heretofore, in most known xerographic heat fusing processes,a temperature control of this nature was difficult to maintain becauseof many variables such as ambient air conditions which were present overwhich there was no control. However, in the present invention atemperature spread of a very few degrees may be accurately maintainedwith little or no difficulty by means of a thermostatic control.

As shown in the preferred embodiment, both lower entrance roll 52 andlower exit roll 59 are mounted on shafts 55 and 57, respectively, whichextends through the housing and are journaled in bearings 62 and mountedin bearing brackets 60. Similarly, upper entrance roll 51 and upper exitroll 58, which are mounted on shafts 54 and 56, respectively, aremounted in an adjustable bearing brackets 60. The bearings brackets areadjustably affixed to the housing and secured thereto by means of screws61 so that the upper and lower rolls may be adjusted to grip in frictiondriving contact a support material inserted therebetween. A hearingbracket gasket 63, fabricated of silicone rubber, is provided betweenthe bearing bracket and the housing to prevent leakage of liquid metal.The upper entrance and exit rolls are driven in synchronization with thebottom driving rolls by means of gears 74 (FIG. 3) fixed to the leftoutboard end of the shafts.

immersing roll affixed to shaft 69 is similarly journaled in bearing 62mounted in adjustable bearing brackets 60.

The lower entrance and lower exit drive shaft extend through the housingand have affixed thereto drive pulley 83. To facilitate proper passageof the support materials through the fuser, housing pulleys 82 and 83are properly sized so that the exit and entrance rolls are driven at thesame peripheral speed as immersing roll 70. Pulleys 82 and 85 areoperutively connected to motor 31 (FIG. I) by means of belt 75.

Alloys of bismuth, lead. and antimony have a high specific gravity (8.2to 10.3) and, therefore, materials such as paper and toner having alower specific gravity will be buoyant in a bath of these metals.lrnmersing roll 70 (FIG. 4) is provided to place the toned image belowthe surface of the hot liquid metal so that both thermal and physicalcontact is maintained between the two. As the support material is beingdriven forward by the entrance rolls, it is guided into the immersingroll by means of a series of guide wires 71 supported on pin 73 mountedin the housing. The guide wire assures that the support material willcontact the positively driven immersing roll at some point below thecenter line causing the support material to be driven under the surfaceof the hot liquid metal. Because roll 70 is partially immersed below thepredetermined level line, liquid metal will be displaced causing anopposite force to be exerted on the support driven thereunder equal tothe amount of metal displaced by the roll. This equal and opposite force(buoyant force) will tend to hold the support material to the immersingroll as it is carried through the hot liquid metal bath.

It should be noted, that in this preferred embodiment, the xerographiccopy is transported through the fuser housing image side down so thatthe image area will come into direct contact with the hot metal.Although the buoyant forces are such to hold the support to theimmersing roll, these forces are insufficient to disturb the toner as itis propelled through the bath.

Heat transfer can be compared to electrical flow in that the lessresistance placed between the source of energy and the body receivingthe energy, the greater will be the amount of energy reaching thereceiving body. By immersing the toner and support material in a bath ofhot liquid metal, the thermal resistance between the heat source and thereceiver will be minimized to produce a rapid and efficient heattransfer.

Upon leaving the immersing roll, support material 25 will float to thesurface of the bath while continuing to be driven forward by thecombined action of the entrance drive rolls and the immersing roll. Thesupport material is guided into contact with exit rolls 58 and 59,respectively, by means of a series of guide wires 71 sup ported on pins73. A series of pickup wires 76 (FIG. 4) suspended in a liquid metal onpin 73, act in cooperation with guide wires 71 to properly align thesupport material in the exit rolls. On leaving the exit rolls thesupport material is guided out of the housing through exit 48 by meansof exit guide plate 64.

It has been found that the buoyant forces exerted on the xerographictoned image, due to the amount of metal displaced by roll 70, aid in thexerographic fusing process. Although this phenomena is not fullyunderstood, it is felt that by forcing the hot liquid metal intointimate Contact with the surface of the xerographically toned image therate of heat transferred is increased.

Pure liquid metal has a corrosive effect when placed in contact withother metals, therefore, it is necessary to provide a protectivecovering on the exposed metal parts on the interior of housing 41. Onceall the parts have been assembled in place. the inside of the housing iscovered with a protective coating of form-retaining wax-like synthetichaving a high melting point. Among such synthetics are:polytetrafiuoroethylene which is sold commercially by the E. l. DuPontde Nemours Company under the trade name Teflon", andpolytrifluorochloroethylene which is sold commercially by the M. W.Kellogg Company under the trade name Kel- F Although this preferredembodiment describes the liquid metal fusing process in reference to aweb support material. it should be obvious to one skilled in the artthat the fuser can be easily adapted to process support material in theform of cut sheets as well as a web.

Slag, which is produced in liquid metals by the oxides of impuritiesfound therein, will bond with the powder image during fusing to give thexerographic toner a slightly metallic luster. Although the bath is to becharged with a pure metal having little or no impurities, it is quitepossible that some impurities will be carried on the support materialinto the bath over a long period of time. it should be noted that thisslag build up will in no way effect the fusing properties of the presentinvention, however, a slightly metallic luster on the finishedxerographic copy may in some cases be commercially undesirable.

FIG. 5 is an embodiment of the present invention in which the supportmaterial is floated across rather than immersed below the surface of thebath so that the toner does not come in contact with the hot liquidmetal. Sufficient heat is transferred by means of convection andconduction through the support material to produce the desired heatfusing. Support material 25 is introduced into the fuser housing throughopening and guided into entrance drive rolls 91 and 92 by means of guideplate 93. Guide wires 89 and 94, located within the housing so as not todisturb the image areas. direct the support material, which is beingtransported across the surface of the hot liquid metal with the imageside up, into contact with exit guide rolls 98 and 99. The exit driverolls 98 and 99 then expel the support material from the housing throughmeans of exit 97. It should be obvious to one skilled in the art thatthe rate of travel of the support material through the fuser can becontrolled so that sufficient time is allowed for heat to be transferredthrough the support material to properly fuse the toner to the support.

While this invention has been described with reference to structuredisclosed herein, it is not confined to the details set forth, and thisapplication is intended to cover such modifications or changes as maycome within the purposes of the improvements or the scope of thefollowing claims.

What is claimed is:

1. Apparatus to heat fix a xerographic toner powder image to a finalsupport material including means to place a toner powder image on afinal support material, means to immerse the image bearing supportmaterial in a bath of liquid metal such that the metal exerts a pressureon the toner image to support the toner in image configuration, and

means to maintain the temperature of the liquid metal at a levelsufficient to uniformly heat the toner powder image to the image fixingtemperature and below the temperature at which the support material isdamaged.

2. Apparatus to heat fix a toner powder image to a final supportmaterial including a housing being adapted to contain a quantity ofliquid material,

a bath of hot liquid metal supported in said container,

said metal having a high specific gravity,

drive means associated with said housing and being arranged to move animage bearing support material through said housing,

an immersing roll positioned in said housing with at least a portion ofsaid roll being supported below the surface of the liquid bath,

means to rotate said immersing roll at a peripheral speed equal to thespeed at which the image bearing support material is being moved throughsaid housing, and

guide member to direct the image bearing support material under saidimmersing roll such that the hot liquid metal exerts a pressure over theentire surface of said toner image wherein the toner powder image isuniformly heated to the fusing temperature by the hot liquid metal inpressure contact therewith.

3. A method of heat fixing a heat fusible toner image to a final supportmaterial includin electrosta ifalw'fita'w jatfidr 'iiii'a (:"dn llt'fmal-sup";-

port material wherein toner particles are loosely bonded to said supportsurface in a raised image configuration,

providing a bath of hot highly dense liquid metal,

maintaining said bath at a temperature at which the toner image is fixedand below a temperature at which the support material is damaged,

moving said image bearing support material below the surface of saidbath wherein the dense hot metal exerts a pressure over the entiresurface of said image to uniformly heat said image to the fusingtemperature.

4. The method of claim 3 wherein said bath is maintained at atemperature between 240F. and 360F.

5. A fusing apparatus for fixing a xerographic image ofthermo-responsive powder located on a support member comprising a heatexchange portion having a heat storage and transfer medium, said mediumfurther comprising a heated liquid which is nonwetting to the supportmember and the image, said liquid heated to a temperature greater thanthe fusing temperature of the thermo-responsive powder and less than thescorch point of the support member,

container means for containing said liquid,

heating means for heating said liquid,

conveying means for conveying the support member with the xerographicpowder image thereon through said heat exchange portion, whereby thexerographic powder images are fixed by heat transfer from said heatstorage and transfer medium to the support member and the powder images.

6. The apparatus of claim 5 wherein said nonwetting liquid is a moltenmetallic alloy.

7. The apparatus of claim 5 wherein said heating means includes controlmeans for maintaining said temperature of said liquid within saidtemperature range.

8. A fusing apparatus for fixing a xerographic image ofthermo-responsive powder located on a support member comprising:

a heat storage and transfer medium for storing heat energy and fortransferring heat energy to the support member having the xerographicpowder image thereon, said medium being a heated liquid that isnon-wetting to the support member and the powder image, said liquidheated to a temperature greater than the fusing temperature of thethermo-responsive powder and less than the scorch point of the supportmember;

container means for containing said liquid;

conveying means for conveying the support member across and in contactwith the surface of said heat storage and transfer medium; and

heat supply means for supplying heat energy to said nonwetting liquid,said nonwetting liquid retaining said heat energy as heat energy,wherein heat transfer from said nonwetting liquid to the support memberand the powder image fixes the powder image.

9. The apparatus of claim 8 wherein said nonwetting liquid is a moltenmetallic alloy.

10. The apparatus of claim 9 including means for positioning saidnonwetting liquid for contacting said supp'ortniember to provide heat tosaid support member, as it passes across said heat storage and transfermedium.

11. The apparatus of claim 9 including means positioning the supportmember and said molten metallic alloy to be in contact with each other,thereby effecting heat transfer to the support member.

12. The apparatus of claim 10 wherein said positioning means is arevolving cylinder partially submerged in said molten alloy.

13. The apparatus of claim 8 wherein said heat supplying means furthercomprises control means to maintain said non-wetting liquid within saidtemperature range.

14. A fusing apparatus for fixing a xerographic image ofthermo-responsive powder located on a support member comprising a heatexchange portion having a heat storage and transfer medium, said mediumcomprising a heated liquid which is nonwetting to the support member andthe image, said liquid heated to a temperature greater than the fusingtemperature of the thermoresponsive powder and less than the scorchpoint of the support member,

container means for containing said liquid,

heating means for heating said liquid,

conveying means for conveying the support r mber with the xerographicpowder image there into contact with said heat transfer and storagemedium, whereby the xerographic powder images ar fixed by heat transferfrom said heat storage and transfer medium to the support member and thepowder image.

15. in the process of making an electrostatically produced copy whereinthermo-responsive particulate material is arranged in a predeterminedpattern on a support member, the improvement comprising contacting thesupport member with a body of liquid sufficient in size and heat contentto effect a thermal fixing of said thermo-responsive particulatematerial without degrading said support member or said thermo-responsiveparticulate material, and maintaining said contact for a time sufficientto thermally fix said thermoresponsive material to said support member.

1. APPARATUS TO HEAT FIX A XEROGRAPHIC TONER POWDER IMAGE TO A FINALSUPPORT MATERIAL INCLUDING MEANS TO PLACE A TONER POWDER IMAGE ON AFINAL SUPPORT MATERIAL, MEANS TO IMMERSE THE IMAGE BEARING SUPPORTMATERIAL IN A BATH OF LIQUID METAL SUCH THAT THE METAL EXERTS A PRESSUREON THE TONER IMAGE TO SUPPORT THE TONER IN IMAGE CONFIGURATION, ANDMEANS TO MAINTAIN THE TEMPERATURE OF THE LIQUID METAL AT A LEVELSUFFICIENT TO UNIFORMLY HEAT THE TONER POWDER IMAGE TO THE IMAGE FIXINGTEMPERATURE AND BELOW THE TEMPERATURE AT WHICH THE SUPPORT MATERIAL ISDAMAGED.
 2. Apparatus to heat fix a toner powder image to a finalsupport material including a housing being adapted to contain a quantityof liquid material, a bath of hot liquid metal supported in saidcontainer, said metal having a high specific gravity, drive meansassociated with said housing and being arranged to move an image bearingsupport material through said housing, an immersing roll positioned insaid housing with at least a portion of said roll being supported belowthe surface of the liquid bath, means to rotate said immersing roll at aperipheral speed equal to the speed at which the image bearing supportmaterial is being moved through said housing, and a guide member todirect the image bearing support material under said immersing roll suchthat the hot liquid metal exerts a pressure over the entire surface ofsaid toner image wherein the toner powder image is uniformly heated tothe fusing temperature by the hot liquid metal in pressure contacttherewith.
 3. A METHOD OF HEAT FIXING A HEAT FUSIBLE TONER IMAGE TO AFINAL SUPPORT MATERIAL INCLUDING ELECTROSTICALLY PLACING A TONER IMAGEON THE FINAL SUPPORT MATERIAL WHEREIN TONER PARTICLES ARE LOOSELY BONDEDTO SAID SUPPORT SURFACE IN A RAISED IMAGE CONFIGURATION, PROVIDING ABATH OF HOT HIGHLY DENSE LIQUID METAL, MAINTAINING SAID BATH AT ATEMPERATURE AT WHICH THE TONER IMAGE IS FIXED AND BELOW A TEMPERATURE ATWHICH THE SUPPORT MATERIAL IS DAMAGED, MOVING SAID IMAGE BEARING SUPPORTMATERIAL BELOW THE SURFACE OF SAID BATH WHEREIN THE DENSE HOT METALEXERTS A PRESSURE
 4. The method of claim 3 wherein said bath ismaintained at a temperature between 240*F. and 360*F.
 5. A fusingapparatus for fixing a xerographic image of thermo-responsive powderlocated on a support member comprising a heat exchange portion having aheat storage and transfer medium, said medium further comprising aheated liquid which is nonwetting to the support member and the image,said liquid heated to a temperature greater than the fusing temperatureof the thermo-responsive powder and less than the scorch point of thesupport member, container means for containing said liquid, heatingmeans for heating said liquid, conveying means for conveying the supportmember with the xerographic powder image thereon through said heatexchange portion, whereby the xerographic powder images are fixed byheat transfer from said heat storage and transfer medium to the supportmember and the powder images.
 6. The apparatus of claim 5 wherein saidnonwetting liquid is a molten metallic alloy.
 7. The apparatus of claim5 wherein said heating means includes control means for maintaining saidtemperature of said liquid within said temperature range.
 8. A fusingapparatus for fixing a xerographic imAge of thermo-responsive powderlocated on a support member comprising: a heat storage and transfermedium for storing heat energy and for transferring heat energy to thesupport member having the xerographic powder image thereon, said mediumbeing a heated liquid that is non-wetting to the support member and thepowder image, said liquid heated to a temperature greater than thefusing temperature of the thermo-responsive powder and less than thescorch point of the support member; container means for containing saidliquid; conveying means for conveying the support member across and incontact with the surface of said heat storage and transfer medium; andheat supply means for supplying heat energy to said nonwetting liquid,said nonwetting liquid retaining said heat energy as heat energy,wherein heat transfer from said nonwetting liquid to the support memberand the powder image fixes the powder image.
 9. The apparatus of claim 8wherein said nonwetting liquid is a molten metallic alloy.
 10. Theapparatus of claim 9 including means for positioning said nonwettingliquid for contacting said support member to provide heat to saidsupport member, as it passes across said heat storage and transfermedium.
 11. The apparatus of claim 9 including means positioning thesupport member and said molten metallic alloy to be in contact with eachother, thereby effecting heat transfer to the support member.
 12. Theapparatus of claim 10 wherein said positioning means is a revolvingcylinder partially submerged in said molten alloy.
 13. The apparatus ofclaim 8 wherein said heat supplying means further comprises controlmeans to maintain said non-wetting liquid within said temperature range.14. A fusing apparatus for fixing a xerographic image ofthermo-responsive powder located on a support member comprising a heatexchange portion having a heat storage and transfer medium, said mediumcomprising a heated liquid which is nonwetting to the support member andthe image, said liquid heated to a temperature greater than the fusingtemperature of the thermo-responsive powder and less than the scorchpoint of the support member, container means for containing said liquid,heating means for heating said liquid, conveying means for conveying thesupport member with the xerographic powder image thereon into contactwith said heat transfer and storage medium, whereby the xerographicpowder images are fixed by heat transfer from said heat storage andtransfer medium to the support member and the powder image.
 15. IN THEPROCESS OF MAKING AN ELECTROSTATICALLY PRODUCED COPY WHEREINTHERMO-RESPONSIVE PARTICULATE MATERIAL IS ARRANGED IN A PREDETERMINEDPATTERN ON A SUPPORT MEMBER, THE IMPROVEMENT COMPRISING CONTACTING THESUPPORT MEMBER WITH A BODY OF LIQUID SUFFICIENT IN SIZE AND HEAT CONTENTTO EFFECT A THERMAL FIXING OF SAID THERMO-RESPONSIVE PARTICULATEMATERIAL WITHOUT DEGRADING SAID SUPPORT MEMBER OR SAID THERMORESPONSIVEPARTICULATE MATERIAL, AND MAINTAINING SAID CONTACT FOR A TIME SUFFICIENTTO THERMALLY FIX SAID THERMO-RESPONSIVE MATERIAL TO SAID SUPPORT MEMBER.